Parts List

Required Parts:

• NRF52840 Dongle

• This is what we're going to program to become our sensor. The NRF52840 chip is probably a bit overkill for this project, but it was the cheapest development board I could find to do ANT+ communication.

• IR Obstacle Detection Sensor

• I had a bunch of these left over from another project so I initially prototyped using one and found it worked very well. This sensor is going to detect the white mark on the treadmill belt.

Other Boards:

These boards would probably work as well, but I haven't tried them and the instructions coming in the following posts might not apply. But if you'd like to work in Arduino or CircuitPython instead of Segger Embedded Studio, one of these might be better.

• SparkFun Pro nRF52840 Mini - Bluetooth Development Board
• Seeed Studio - nRF52840 Micro Development Kit
• Adafruit - Feather nRF52840 Express
• Adafruit - Particle Xenon nRF52840 with BLE and Mesh

Miscellaneous Parts and Tools:

• Plastic Project Box
• Holds all of the electronics and provides a bit of protection against sweat and misplaced footsteps.
• USB Extension Cable
• The USB interface of the NRF52840 dongle makes it really easy to power the board off of a USB extension cable and USB wall charger. Using an extension cable also provides a mounting point for the dongle.
• USB Wall Charger
• If you're using the USB extension cable to power the NRF52840 dongle you can plug it right into a USB wall charger. I just repurposed one of the many of these I had lying around the house.
• Wire
• To connect the NRF52840 dongle to the IR Obstacle Detection Sensor. 
• Dupont Connectors
• If you'd like to connect the boards with a removable cable instead of direct soldering
• Cable Crimper
• To build the Dupont connectors
• Soldering Iron
• I don't think there's going to be a way around this. You're going to need to solder something to the NRF52840 dongle, whether it be header pins, wires, or the IR sensor itself. A less expensive option will also work just fine and you'll get some solder in the kit.
• Solder
• This one's kind of obvious if soldering is involved.
• Header Pins (3 pins)
• These will solder to the NRF52840 dongle's castellated pads really well and allow the cable with Dupont connectors to be removed. Alternatively, just solder the wires directly to the pads.
• Hot Glue or Epoxy
• I used quite a bit of hot glue to hold everything together inside of the project box and to secure the NRF52840 to the USB extension cable.
• Packing/Duct Tape, Double-Sided Tape, or Dual Lock Tape
• You'll need something to hold the project box to the treadmill. I've tested using masking tape and packing tape. The final attachment will be with dual lock tape only because I already have some. If not, I'd go with the double-sided tape.
• White Paint
• To make a mark on the treadmill belt for the optical sensor. I tried tape but it always flew off in the middle of a run.

Helpful for Debugging

• Suunto Movestick Mini
• Works with SimulANT+ (ANT+ simulator software) capable of simulating ANT+ sensors and displays.
• This also works really well with the ANT+ Python libraries and Raspberry Pi. I prototyped this project on a Raspberry Pi using Python.
• Digital Multimeter
• For reading voltage, checking for continuity, and looking for shorts. This doesn't need to be very fancy, a multimeter with DC voltage measurements and continuity checker will do.

Next up, we're going to talk about how to connect the NRF52840 dongle and IR sensor.

Note: The links above may be affiliate links.  I debating making them as such, but decided to go for it. The items don't cost any extra for you and I earn a small commission on your purchases. Thanks for helping to support this project, I appreciate it. I'll enjoy an adult beverage because of your support.